Bulky articles such as pieces of furniture are typically assembled at a manufacturing facility according to custom instructions based upon a customer or retailer order. Because of a wide variety of styles, constructions, fabrics, and the like within a single manufacturer's catalog, because such items are comparatively expensive, and because of traditional production practices, it is common for a furniture manufacturing facility to produce pieces of furniture of differing lengths on a piece-by-piece basis, rather than manufacturing a run of a single style all at the same time.
Because these articles often utilize valuable materials and skilled handiwork, and because they must be shipped great distances and protected during shipment, it is common to place each article in a plastic bag together with some sort of padding element. The automation of this process has resulted in the common use of a bag formed substantially as follows. A layer of foam or other suitable padding element is sandwiched between two layers of plastic film and sealed along its longitudinal edges. The sandwich is then folded along a central longitudinal line to form an envelope, and the envelope is made into a bag of an appropriate length by end-seal-cutting at longitudinally spaced locations corresponding to the desired length. The bag may then be placed over the bulky article so that the padding element surrounds the bulky article.
It is typical for these bags to be manufactured by a bag manufacturer in a series of standard sizes and provided to the furniture manufacturer on rolls or in packages of bags, sized based upon the largest item in the furniture manufacturer's catalog.
Those who are skilled in the art of furniture packaging will recognize that the padding element, which is generally opaque (as opposed to the generally transparent film), serves to obstruct easy vision of the article contained within the bag. As the bulky article may be held in a warehouse prior to delivery, a warehouse worker seeking to identify the article, which is generally a custom item specific to a particular customer's order, must generally rely on markings on the bag or open each bag to identify the desired article.
However, it has also been recognized that the type of damage against which the padding element protects is generally only realized at the ends of each piece, such as on the arms of a sofa. Therefore, one practice is to dispose the padding element only at the ends of the bag, leaving a “window” for the easy identification of the contents of the bag. This allows the bag manufacturer to realize a materials costs savings while providing for easier warehousing processes, but doing so introduces special difficulties into the manufacturing process. U.S. Pat. No. 6,428,459, the disclosure of which is incorporated herein by reference, identifies a method of forming a windowed bag for a bulky article which overcomes many of the special difficulties associated therewith.
A manufacturer offering numerous sizes of furniture, all custom-produced on a piece-by-piece basis at a single manufacturing point, must decide how many bags of each size to keep in stock, and this decision may hinge upon the suitability of a particular standard-size bag for use with a particular size of a piece of furniture. The risk associated with using a bag that fits the item improperly is that the item will incur damage during shipment, which results in a loss to the manufacturer and irritation and delay on the part of the customer. However, given a wide variety of sizes and the unpredictable nature of the business of custom furniture manufacturing, it is often economically infeasible to carry a supply of pre-made bags of every size needed, particularly if the bags vary both in their length and in the arrangement of the padding element. Most manufacturers keep only one to three sizes of bags in stock, each sized for the largest sofa, love seat, and chair, for instance, in the manufacturer's catalog. This practice is wasteful of bagging materials when these bags are used on smaller items.
It would therefore be helpful if a manufacturer could produce bags of custom sizes on a per-piece basis, such that a custom bag of exactly the right length and exactly the right padding element arrangement is produced only when needed.
A further problem associated with the formation of bags is in the length of the production line needed to form a single windowed bag. A typical arrangement for forming windowed bags includes two rolls of plastic film and a roll of padding element, which are rolled out into a sandwich, center-folded, and seal-cut along the ends to a desired length. If a windowed bag is to be formed, however, the padding element must be cut and the feeding of the padding element roll stopped briefly in relation to the feeding of the film rolls to form the region in which no padding element is present. It can be rather easily appreciated that this cut must be made before the sandwich is folded, and indeed just as the sandwich is formed; otherwise, access to the padding element is not available.
However, in a typical bag forming apparatus, the distance along the production line required for forming the sandwich, folding the sandwich, and sealing the end is longer than a typical bag, and may in some cases be longer than the total length of two, three, or more bags. This does not present a problem when bags of the same size are formed all at the same time, but if only a single bag of a custom size and arrangement is needed, then a substantial amount of waste is generated as the rolls must be advanced far enough to allow that custom bag to reach the end of the production line.
A further problem associated with the formation of windowed bags is the tendency of the padding element to shrink away from the heat sealing mechanism and to become disconnected within the film-pad sandwich. The ends are typically seal-cut using a hot wire sealing arrangement that is applied with a temperature sufficient to capture the end of the padding element within the seal by melting it into the thermoplastic. However, because the padding element is largely free to “float” within the sandwich, if a hot wire is applied to the seal-cut location, the unmelted portion of the padding element tends not to remain integral with the melted portion of the padding element, and this separation allows the unmelted portion to float freely. This is undesirable because the padding element needs to remain at the ends of the bag. This problem could be solved by attaching the padding element along its face to the film layers, but this would reduce the effectiveness of the padding element to prevent damage to the bulky article, and in certain applications (such as shrink-wrapping applications) may cause the padding element to become rumpled.
What is needed, then, is a bag forming apparatus and method that overcomes the noted disadvantages of conventional systems to allow single window bags of custom sizes and configurations to be produced in a desired order on a single machine, in such a manner that the padding elements are captured at their ends in the end-seals.